Armature-contact rod connection for current-limiting breaker

ABSTRACT

A current-limiting circuit breaker is provided with a new and improved contact-operating assembly having a contact rod operatively joined to a tubular operating shaft by an axially extending stepped connector fixedly received within the rod and slidably retained by the operating shaft to permit limited relative movement between the operating shaft and the contact rod of the assembly. A spring mounted within the tubular shaft acts on the connector and may be adjusted independently of shaft movement.

United States Patent Nonnan R. Beaudoin Bristol;

Robert W. Lauben, Farmington, both of, Colo.

Oct. 15, 1969 May 25, 1971 General Electric Company Inventors App]. No.Filed Patented Assignee ARMATURE-CONTACT ROD CONNECTION FORCURRENT-LIMITING BREAKER 9 Claims, 4 Drawing Figs.

US. Cl 335/16 Int. Cl ..H0lh 77/10 Field of Search 335/16;

ZOO/153.20

[56] References Cited UNITED STATES PATENTS 3,025,375 3/1962 FrankZOO/153.20 3,258,549 6/1966 Stoi ZOO/153.20 3,384,845 5/1968 Johnson335/16 Primary Examiner-Harold Broome Att0rneysRobert S. Smith, RobertT. Casey, D. M. Schiller,

Frank L. Neuhauser, Oscar B. Waddell and Joseph B. FormanARMA'I'URE-CONTACT ROD CONNECTION FOR CURRENT-LIMITING BREAKERBACKGROUND AND SUMMARY OF THE INVENTION The present invention relatesgenerally to electric circuit breakers and is more particularlyconcerned with circuit breakers of the circuit-limiting" type havinglinearly movable contact-operating assemblies.

Recently electric circuit breakers have been developed which combineconventional manual and automatic operation with an unfused high-speedcurrent interruption capability. Typical of such circuit breakers whichhave proved particularly effective in combining the conventional andcurrentlimiting means for causing opening of the contacts is thestructure disclosed in US. Pat. No. 3,384,845 issued on May 21, 1968 toJohnson et al. and assigned to the same assignee as the presentinvention. As set forth in that patent, the currentlimiting circuitbreaker is provided with a linearly movable contacboperating assemblyoperatively, associated with both a conventional operating mechanism anda high-speed solenoid operator. The assembly includes a contact rodsupportably mounting an armature of the solenoid operator and a tubularoperating shaft connected to the contact rod by means of a spring-biasedlost-motion connection consisting of an elongated slot within which isslidably received a transversely extending roll pin. As can beappreciated, high-speed operation of the assembly by the solenoid placessubstantial stress forces on the assembly particularly at thelost-motion connection. Additionally, the connection utilized heretoforeprevents adjustment of the spring-biasing force without also varying thewear allowance of the assembly.

Accordingly, it is an object of the present invention to provide a newand improved current-limiting circuit breaker hav-- ing a linearlymovable contact-operating assembly including an axially extendinglostmotion connector promoting greater reliability of operation andpositive driving engagement between the armature and the tubularoperating shaft during opening of the contacts under high short circuitcurrent conditions.

It is another object of the present invention to provide a new andimproved current-limiting circuit breaker of the type described whichincorporates a new and improved axial connection between the operatingshaft and the contact rod of the contact-operating assembly. Theconnection provides greater convenience of assembly and a neater, morepleasing appearance while at the same time assuring adjustability ofcontact pressure without variation in the wear allowance.

Other objects will be in part obvious and in part pointed out more indetail hereinafter.

Briefly stated, these and related objects are accomplished in accordancewith the present invention by incorporating into a current-limitingcircuit breaker a newand improved contactoperating assembly having acontact rod operatively joined to a tubular operating shaft by anaxially extending stepped connector fixedly received within the rod andslidably retained by the operating shaft to permit limited relativemovement between the operating shaft and the contact rod of theassembly. A spring mounted within the tubular shaft acts on theconnector and may be adjusted independently of shaft movement.

A better understanding of the invention will be obtained from thefollowing detailed description and accompanying drawings which set forthan illustrative embodiment and are indicative of the way in which theprinciple of the invention is employed.

BRIEF DESCRIPTION OF THE DRAWINGS In the Drawings: FIG. 1 is a sideelevational view, partly broken away and partly in section, illustratinga portion of the internal mechanism of a current-limiting circuitbreaker incorporating the features of the present invention;

FIG. 2 is an enlarged partial side elevational view, partly broken awayand partly in section, illustrating the relative positioning of thecontact-operating assembly of FIG. 1 during normal closed-circuitoperation;

FIG. 3 is a view similar to FIG. 2 showing the position of thecontactoperating assembly after response to a high-level short circuitcurrent condition but prior to full trip operation of the circuitbreaker's conventional operating mechanism; and

FIG, 4 is a view similar to FIG. 3 showing the position of thecontact-operating assembly when the circuit breaker is manually set atits OFF position.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to the drawings ingreater detail wherein like reference numerals indicate like partsthroughout the several figures, the invention is illustrated as embodiedwithin a current-limiting circuit breaker having a generally rectangularhousing 12 including an insulating cover 14 provided with an elongatedcentral aperture 16 through which extends a manually operated handle 18.Although the housing 12 encloses three separate and individual polesextending longitudinally along the breaker, the mechanism associatedwith only one of the three poles will be described in order to providegreater ease of understanding and clarity of description. It will, ofcourse, be understood that manual operation of the handle I8 will effectsimultaneous opening and closing of the circuits controlled by thebreaker while automatic opening of one circuit will cause acorresponding open circuit condition within the entire circuit breaker.Referring specifically to FIGS. 1 and 2, a pair of spaced stationarycontacts 22 are shown as fixedly mounted on separate arc runners 24within the housing 12. The contacts 22 are positioned within anarc-initiating chamber 26 and are electrically connected throughsuitable conductive straps to line and load terminals 23, 30,respectively, positioned at opposite ends of the circuit breaker. A pairof complementary movable contacts 34 operatively connected to a linearlymovable contact-operating assembly, generally designated by the numeral36, reciprocally move toward and away from the stationary contacts 22between open and closed circuit positions. A trip unit 38 supportedwithin the housing 12 adjacent the load terminal 30 is electricallyconnected to one of the stationary contacts 22 by a trip unit strap 40and is mechanically connected to the linearly movable contact assembly36 through a conventional overcenter operating mechanism 42 operativelyassociated with the handle 18.

It will be appreciated that the manual and automatic operation of thecurrent-limiting circuit breaker of the present invention issubstantially the same as that described in the aforementioned Johnsonet al. US. Pat. No. 3,384,845. Accordingly, when the manually operatedhandle 18 is moved out of its ON position shown in FIG. 1 toward its OFFposition, the overcenter operating mechanism 42 will cause a common tiebar 46 to rotate clockwise as viewed in FIGS. 1 and 2. During thismovement a high-speed connecting plate 48 connected to the assembly 36will move with the tie bar 46 as a result of the driving engagementbetween the pin 50 and the end of slot 52 in plate 48. In this manner,the entire linearly movable contact-operating assembly 36 is drawn tothe right as viewed in FIGS. 1 and 2 until it assumes the open circuitposition illustrated in FIG. 4.

When the circuit breaker is in the ON position shown in FIGS. 1 & 2 anda low value short circuit current conditions occurs, the trip unit 38will release a releasable latch 54 thereby pennitting a shift in theovercenter operating mechanism 42 and opening of the contacts insubstantially the same manner as indicated for the movement of thehandle 18 to its OFF position. As set forth in the aforementionedJohnson et al. US. Pat. No. 3,384,845, during high-level short circuitconditions the slot in connection plate 48 permits movement of thecontacts to an open circuit position by'the high-speed solenoid operator56 independently of the operation of the conventional operatingmechanism 42.

Referring particularly to the illustrated embodiment of FIGS. 2-4, thelinearly movable contact-operating assembly 36 includes an elongatedtubular operating shaft 58 extending from the mechanism 42 axiallythrough the central aperture 60 of the solenoid operator 56. The shaft58 is operatively connected to the mechanism 42 by an adjustable linkage62 secured by the pin 64 to the connecting plate 48 for movementtherewith. The linkage 62 includes an insulated plug member 66threadably received within one end of the tubular operating shaft 58 andan axially projecting bifurcated connecting link 68 threadably receivedwithin the plug member 66.

Spaced from the operating shaft 58 and in substantial coaxial alignmenttherewith is a solid contact rod 72 having a contact carrier 74 ofgenerally trapezoidal shape fixedly mounted on its forward end. Asshown, the carrier 74 supports the movable contacts 34 on the flatangularly disposed end surfaces 76 thereof for movement toward and awayfrom stationary contacts 22 mounted on the arc runners 24. The oppositeend of contact rod 72 is provided with a hub portion 82, FIG. 2, ofreduced cross section forming a shoulder abutment 84 against which issecured a thin disclike heat fin 86 disposed normal to the axis of thecontact rod. Mounted on the hub portion 82 adjacent the heat fin is agenerally cylindrical armature 88 for the solenoid operator 56, thearmature 88 including a radially extending flange 90 in intimate surfacecontact with a flat face of the disclike heat fin 86. The armature 88 isfixedly secured to the contact rod and is disposed in telescopicallyslidable relationship with the end of the operating shaft adjacent thecontact rod.

ln accordance with the present invention a threaded connector of steppedconfiguration is secured within both the operating shaft 58 and thecontact rod 72 and maintains the shaft and rod in close, relativelymovable relationship while providing a lost-motion connectiontherebetween. The connector extends coaxially of both the shaft and therod and includes anenlarged head portion 94 positioned within thetubular shaft 58 forinterfering engagement with an inwardly projectinglip 96 located on the end of shaft 58 opposite linkage 62. The headportion 94 is of sufficient size relative to the port defined by lip 96to prevent removal thereof from the shaft in the direction of thecontact rod 72. Integral with but spaced from the head portion 94 is theconnectors threaded stem portion 98 fixedly received within the axialextending aperture 100 provided in the hub portion 82 of the contactrod. An elongated, generally cylindrical shank portion 102 integrallyconnects the head portion 94 and stem portion 98 of the connector, theshank portion being of a size capable of being slidably received withinthe communicating port defined by the inwardly projecting lip 96 of theoperating shaft. The shank portion 102 is substantially uniform in crosssection along its length and of greater diameter than the stem portion98 so as to provide a retaining shoulder 106 which bears against theradial flange 90 of the solenoid armature 88 urging it into retainedengagement with the heat fin 86. Thus, both the heat fin 86 and solenoidarmature 88 are fixedly secured to the contact rod 72 and retainedthereon for movement with the rod through the cooperative action of therods shoulder abutment 84 with the retaining shoulder I06 of theconnector. As will be appreciated, movement of the armature 88 by thesolenoid operator 56 will be effective to simultaneously drive thecontacts out of a closed circuit position, the solenoid being designedto cause movement of the armature upon the occurrence of a high-levelshort circuit current condition.

Mounted within the tubular operating shaft 58 and extendinglongitudinally thereof from the plug member 66 is a contact spring 108which operatively bears against the head portion 94 of the connectorurging it toward engagement with the shal't's inwardly projecting lip96. It is an advantageous feature of the present invention that thebiasing force of spring 108, and therefore the contact pressure to beovercome by the solenoid 56, can be adjusted without requiring movementof the shaft 58 relative to the contact rod 72. As mentionedhereinbefore, the movable contacts can be readily moved into a closedcircuit position by manually moving the operating lever 18 from the OFFposition to the ON position. When the manually operated handle is in theOFF position the compression spring 108 urges the head portion 94 of theconnector into firm abutting engagement with the inwardly projecting lip96 of the operating shaft, as shown in FlG. 4. However, as the linearlymovable contact-operating assembly 36 is moved to the left toward theclosed circuit position shown in FIGS. I and 2 the movable contacts 34come into abutting engagement with the stationary contacts 22. Continuedmovement of the overcenter operating mechanism 42 causes the operatingshaft 58 to slidably move along the shank portion 102 of the connectoragainst the bias of spring 108 thereby further loading the spring andassuring firm positive contact between the movable and stationarycontacts of the circuit breaker. Thus, as shown in FlGS. l and 2, a weargap, indicated by the numeral 112, is provided between the inwardlyprojecting lip 96 of the operating shaft 58 and the head 94 of theconnector. As can be appreciated, the gap 112 can be varied in size andthe loading of the spring 108 can be adjusted by appropriate axialmovement of linkage members 66 and 68. In this way greater control canbe exercised over the contact pressure and thus over the force whichmust be generated within the solenoid to cause separation of thecontacts. Additionally, as can be clearly seen, the forces acting withinthe movable contact assembly are substantially concentrated along theaxis of the assembly while avoiding a transversely extending connectionbetween the operating shaft and the contact rod.

Upon the occurrence of a high-level short circuit current conditionacross the circuit breaker the energized solenoid 56 attracts themagnetically responsive armature 88 causing rearward movement thereof tothe right as viewed in the drawings. lt will be appreciated that onlythe force exerted by the loaded spring 108, which is less than that ofthe overcenter operating mechanism 42, need be overcome by the solenoidto cause opening of the contacts. The high-speed operation of thesolenoid operator 56 causes rapid rearward movement of the armature 88,contact rod 72 and those members fixedly connected thereto. This action,of course, causes additional loading of the compression spring 108 andrapidly brings the radially extending flange of the armature intodriving engagement with the inwardly projecting lip 96 on the operatingshaft. ln this manner the armature 88 directly drives the operatingshaft 58 rearwardly causing the high-speed connecting plate 48 to rotateto the phantom position illustrated in FlG. 2 against the bias of itsretaining spring 114.

Thus, the solenoid will drive assembly 36 into the position shown inFIG. 3. However, as mentioned in the Johnson et al. U.S. Pat. No.3,384,845, the slot in plate 48 permits this rapid movement withoutinterference from the slower-moving overcenter operating mechanism 42.Although the short cir-' cuit current condition will be effective tocause the trip unit 38 to release the releasable latch 54 and trip theovercenter mechanism 42, it will be appreciated that the opening of thecontacts is not delayed so as to await activation of the trip unit. Ofcourse, the open circuit condition of the tripped circuit breaker willdeactivate the solenoid and permit the spring 108 to drive the headportion 94 of the connector into the rest position shown in FIG. 4 inabutting engagement with the lip 96.

As can be seen from the foregoing detailed description, the presentinvention provides a stepped axially aligned connector between theoperating shaft and the contact rod of a linearly movablecontact-operating assembly. This construction provides reliability ofoperation and enables direct driving engagement between the flange 90 ofthe armature and the operating shaft 58 during high-speed operation.Additionally,

the assembly provides a neuter appearance and permits greateradjustablility and control over the contact. pressure during closedcircuit operation.

As will be apparent to persons skilled in the art, variousmodifications; adaptations and variations of the foregoing specificdisclosure can be made without departing from the teachings of thepresent invention.

What we claim is new and desire to secure by Letters Patent of theUnited States is:

1. An electric circuit breaker comprising:

a. a support;

b. a pair of relatively movable contacts mounted on the support formovement between open and closed circuit positions;

. and a linearly movable contact'operating assembly comprising;

an elongated operating shaft spaced from the contacts;

e. a linearly extending contact rod operatively positioned intermediatethe contacts and the operating shaft, said rod being fixedly connectedto at least one of said contacts for movement therewith between open andclosed circuit positions, said shaft being generally in axial alignmentwith the rod;

f. an axially extending connector joining the operating shaft to thecontact rod while permitting limited relative movement there between;

. said connector having an axially extending stepped configurationincluding a central shank portion positioned within the space betweenthe contact rod and the operating shaft and a pair of terminalconnecting portions on opposite ends of the shank portion for secureretention by the rod and shaft respectively.

2. The electric circuit breaker of claim 1 wherein the operating shaftis atubular member provided with an inwardly extending projection at anend thereof, the connector is secured to the contact rod and has anenlarged head portion in interfering engagement with the projection forretention of the head portion within the shaft.

3. The circuit breaker of claim 1 including a current-responsive drivemember operatively connected to the relatively movable contacts formovement thereof to an open circuit position upon the occurrence ofpredetermined current conditions through the contacts; the connectorhaving a stem secured to the contact rod, an enlarged head portionspaced from the rod and movably connected to the operating shaft and aretaining shoulder spaced from the head portion for retaining the drivemember in fixed spaced relationship to the head portion.

4. The circuit breaker of claim 1 including a high-speed drive memberfixedly secured to the contact rod for moving the contacts to an opencircuit position upon the occurrence of predetermined current conditionsthrough the contacts, the operating shaft having an abutment on the endthereof, said drive member having a shaft-driving face portion in spacedrelationship with the operating shaft for movement into drivingengagement with the abutment upon the occurrence of said predeterminedcurrent conditions.

5. The electric circuit breaker of claim 1 wherein the contact rodincludes a shoulder abutment, the circuit breaker including a drivemember mounted on the contact rod adjacent the shoulder abutment, theconnector having a stem portion secured to the contact rod and anelongated shank portion including a retaining shoulder abutting thedrive member and cooperating with the shoulder abutment on the contactrod for confinably retaining the drive member therebetween in fixedrelationship to the contact rod.

6. The circuit breaker of claim 1 including a generally cylindricalsolenoid armature in telescopically slidable relationship with theoperating shaft, the armature having a radial shaftdriving flangenormally biased into spaced relationship with the operating shaft formovement into driving engagement therewith upon the occurrence ofpredetermined current conditions.

7. The electric circuit breaker of claim 1 wherein the operating shaftis a tubular member provided with an inwardly projecting lip definin acommunicating port of reduced cross sec 10!! at the end 0 the shaft adacent the contact rod; the

, connector is secured to the contact rod and has an enlarged headportion positioned within the tubular shaft in interfering engagementwith the inwardly projecting lip for retention of the head portionwithin the shaft and an elongated shank portion freely extending throughthe communicating port and including a retaining shoulder spaced fromthe head portion, the circuit breaker including a solenoid armatureconfinably retained on the contact rod by the retaining shoulder andspring means adjustably mounted within the tubular shaft for actingagainst the head portion and urging. it toward engagement with theinwardly projecting lip.

8. The electric circuit breaker of claim 1 wherein the contact rodincludes an axially apertured hub portion of reduced cross sectionproviding a shoulder abutment; the operating shaft is-a tubular memberprovided with an inwardly projecting lip defining a communicating portof reduced cross section at the end of the shaft adjacent the contactrod; the connector includes a threaded stem portion threadably receivedwithin the axial aperture of the hub portion, an enlarged head portionpositioned within the tubular shaft in interfering engagement with theinwardly projecting lip for retention of the head portion within theshaft and an elongated shank portion integrally joining the stem andhead portions, said shank portion freely extending through thecommunicating port for axial movement relative to the shaft andincluding a retaining shoulder spaced from the head portion, the circuitbreaker including a high-speed current-responsive drive member mountedon the hub portion, said retaining shoulder abutting the drive memberand cooperating with the shoulder abutment on the contact rod forconfinably retaining the drive member therebetween in fixed relationshipto the contact rod.

9. The circuit breaker of claim 8 wherein the high-speedcurrent-responsive drive member is a generally cylindrical solenoidarmature mounted in telescopically slidable relationship with theoperating shaft, the circuit breaker including a spring mounted withinthe tubular shaft for urging the armature away from the shaft, thearmature including a radial flange normally spaced from the lip of thetubular shaft for movement into driving engagement therewith against thebias of the spring upon the occurrence of predetermined currentconditions.

1. An electric circuit breaker comprising: a. a support; b. a pair ofrelatively movable contacts mounted on the support for movement betweenopen and closed circuit positions; c. and a linearly movablecontact-operating assembly comprising; d. an elongated operating shaftspaced from the contacts; e. a linearly extending contact rodoperatively positioned intermediate the contacts and the operatingshaft, said rod being fixedly connected to at least one of said contactsfor movement therewith between open and closed circuit positions, saidshaft being generally in axial alignment with the rod; f. an axiallyextending connector joining the operating shaft to the contact rod whilepermitting limited relative movement there between; g. said connectorhaving an axially extending stepped configuration including a centralshank portion positioned within the space between the contact rod andthe operating shaft and a pair of terminal connecting portions onopposite ends of the shank portion for secure retention by the rod andshaft respectively.
 2. The electric circuit breaker of claim 1 whereinthe operating shaft is a tubular member provided with an inwardlyextending projection at an end thereof, the connector is secured to thecontact rod and has an enlarged head portion in interfering engagementwith the projection for retention of the head portion within the shaft.3. The circuit breaker of claim 1 including a current-responsive drivemember operatively connected to the relatively movable contacts formovement thereof to an open circuit position upon the occurrence ofpredetermined current conditions through the contacts; the connectorhaving a stem secured to the contact rod, an enlarged head portionspaced from the rod and movably connected to the operating shaft and aretaining shoulder spaced from the head portion for retaining the drivemember in fixed spaced relationship to the head portion.
 4. The circuitbreaker of claim 1 including a high-speed drive mEmber fixedly securedto the contact rod for moving the contacts to an open circuit positionupon the occurrence of predetermined current conditions through thecontacts, the operating shaft having an abutment on the end thereof,said drive member having a shaft-driving face portion in spacedrelationship with the operating shaft for movement into drivingengagement with the abutment upon the occurrence of said predeterminedcurrent conditions.
 5. The electric circuit breaker of claim 1 whereinthe contact rod includes a shoulder abutment, the circuit breakerincluding a drive member mounted on the contact rod adjacent theshoulder abutment, the connector having a stem portion secured to thecontact rod and an elongated shank portion including a retainingshoulder abutting the drive member and cooperating with the shoulderabutment on the contact rod for confinably retaining the drive membertherebetween in fixed relationship to the contact rod.
 6. The circuitbreaker of claim 1 including a generally cylindrical solenoid armaturein telescopically slidable relationship with the operating shaft, thearmature having a radial shaft-driving flange normally biased intospaced relationship with the operating shaft for movement into drivingengagement therewith upon the occurrence of predetermined currentconditions.
 7. The electric circuit breaker of claim 1 wherein theoperating shaft is a tubular member provided with an inwardly projectinglip defining a communicating port of reduced cross section at the end ofthe shaft adjacent the contact rod; the connector is secured to thecontact rod and has an enlarged head portion positioned within thetubular shaft in interfering engagement with the inwardly projecting lipfor retention of the head portion within the shaft and an elongatedshank portion freely extending through the communicating port andincluding a retaining shoulder spaced from the head portion, the circuitbreaker including a solenoid armature confinably retained on the contactrod by the retaining shoulder and spring means adjustably mounted withinthe tubular shaft for acting against the head portion and urging ittoward engagement with the inwardly projecting lip.
 8. The electriccircuit breaker of claim 1 wherein the contact rod includes an axiallyapertured hub portion of reduced cross section providing a shoulderabutment; the operating shaft is a tubular member provided with aninwardly projecting lip defining a communicating port of reduced crosssection at the end of the shaft adjacent the contact rod; the connectorincludes a threaded stem portion threadably received within the axialaperture of the hub portion, an enlarged head portion positioned withinthe tubular shaft in interfering engagement with the inwardly projectinglip for retention of the head portion within the shaft and an elongatedshank portion integrally joining the stem and head portions, said shankportion freely extending through the communicating port for axialmovement relative to the shaft and including a retaining shoulder spacedfrom the head portion, the circuit breaker including a high-speedcurrent-responsive drive member mounted on the hub portion, saidretaining shoulder abutting the drive member and cooperating with theshoulder abutment on the contact rod for confinably retaining the drivemember therebetween in fixed relationship to the contact rod.
 9. Thecircuit breaker of claim 8 wherein the high-speed current-responsivedrive member is a generally cylindrical solenoid armature mounted intelescopically slidable relationship with the operating shaft, thecircuit breaker including a spring mounted within the tubular shaft forurging the armature away from the shaft, the armature including a radialflange normally spaced from the lip of the tubular shaft for movementinto driving engagement therewith against the bias of the spring uponthe occurrence of predetermined current conditions.